Severe pitch up on takeoff

[Nealius]

I keep having issues with a severe pitch up moment after takeoff, even with pitch trim set 1.5 notches nose down. It seems to be worse when flying missions like DCS Liberation. Taking off with about +10 boost, easing the stick to neutral for the tail wheel to come up, then easing the stick back maybe 5mm to come off the ground. What am I doing wrong here? 

[Hunter Joker]

Put the pitch trim down to one notch and it will go like a charm.

[Nealius]

1 hour ago, Hunter Joker said:

Put the pitch trim down to one notch and it will go like a charm.
 

 

As I mentioned in my post, I always set pitch trim to 1 notch or even 1.5 notches down and still get a severe pitch up moment, almost going into a left wing stall unless I shove the stick forward. 

[philstyle]

make sure your flaps are up.

and go easy on the throttle. 10lb is enough boost for takeoff

Edited December 28, 2020 by philstyle

[DD_Fenrir]

Nealious, is this just after lift off? Do you leave the ground and it happens a few seconds after you get some air under the wheels?

[Art-J]

FFB stick or not? I recall reading about a bug with FFB sicks long ago, where the trim indicator would work, but the trim itself would not. I don't know if it's still a problem in latest versions, though.

 

Also, the trim doesn't work when using "game flight mode" (or whatever it's called), but I suppose that doesn't apply to a veteran you?

Edited December 28, 2020 by Art-J

[Nealius]

No FFB stick. Game flight mode off. Flaps up. It happens almost as soon as the wheels leave the ground. It's more severe at +10 boost, going into a near wing-stall, but still occurs at +8 boost minus the near wing-stall.

 

I'm running a TM Warthog on a 20cm extension, so I could be pulling the stick back more than I think, but I'm fairly certain I'm barely touching it. I'll try some takeoffs with the controls indicator and the stick mostly neutral to see what happens. 

Edited December 29, 2020 by Nealius

[Art-J]

Any other FFB devices plugged into PC then? Even if not used in DCS (racing wheel or gamepad for example)?

[grafspee]

Upload track if you can.

Honestly i don't think so that boost has any impact on pitching problem, i take off with 18lbs and plane does not experience extreme pitch up problems.

maybe you just pull stick too much too early.

https://youtu.be/2RzDCDODrTY

Edited December 29, 2020 by grafspee

[Nealius]

It looks like the problem is me hamfisting the stick. If I leave it neutral she will come off the ground nicely, but you can still feel the planes desire to go nose up.

[zcrazyx]

6 hours ago, Nealius said:

It looks like the problem is me hamfisting the stick. If I leave it neutral she will come off the ground nicely, but you can still feel the planes desire to go nose up.

most aircraft will have a tendancy to pitch with power especially at lowers speeds, you could attempt to keep the nose down and the wheels on the ground a little longer, or perhaps alternatly three pointing it off the ground and gradually trimming it. 

 

curves are a major help as does having the right trim, you may find the manuals suggest one thing but you are better with a different setting.

[Helles Belle]

I find the pitching up after takeoff associated with the gear. You’ll really notice the opposite during approach when you put the gear down it pitches down. Same with the flap. As @philstyle said don’t use flaps for take off and try using only 10-12 boost.

I have the nose down & rudder right trim mapped to two buttons side by side on the keyboard.

I find if you press both until nose trim indicates 1 unit UP, the rudder trim will be right for takeoff.

Slowly bringing the power up to 10-12 boost it almost lifts off the ground by itself and flies away.

 

 

[grafspee]

While taking off AOA is high and power is max this induce pitch up. but this is not something that you can not control with your stick.

for spitfire take off you should use neutral trim so 2 notch down from initial trim, once you get more speed this this trim induce very nose heavy attitude, so you need to trim 1 notch up at least when you get speed.

I take off 18lbs/3000rpm trim neutral require no back pressure from me, plane lift off on its own, only thing what i need to do is to apply some right aileron and rudder to keep it straight

 

[Mangrove Jack]

I was in all sorts of problems in take-off with 1 notch of nose down. I was getting swing lefts and wing stalls and probably too much power. Keep going the opposite direction with the trim and have finished at 1 notch up in trim and keep below or at 8 boost and it seems to now fly off nicely. I sometimes wonder if the actual joystick response is an influencer from 1 person to another (I seem to think I have seen difference in the centring location of the joystick when you show the control graphic). I don't use curves at all. After all that I came to conclusion - if aircraft not doing what you want - change what you are doing and that took me too long to work out lol?

[grafspee]

6 hours ago, Mangrove Jack said:

I was in all sorts of problems in take-off with 1 notch of nose down. I was getting swing lefts and wing stalls and probably too much power. Keep going the opposite direction with the trim and have finished at 1 notch up in trim and keep below or at 8 boost and it seems to now fly off nicely. I sometimes wonder if the actual joystick response is an influencer from 1 person to another (I seem to think I have seen difference in the centring location of the joystick when you show the control graphic). I don't use curves at all. After all that I came to conclusion - if aircraft not doing what you want - change what you are doing and that took me too long to work out lol?

Flight manual advice to use neutral elevator trim this mean 2 notch down from initial position.

[DD_Fenrir]

10 minutes ago, grafspee said:

Flight manual advice to use neutral elevator trim this mean 2 notch down from initial position.

 

Er.... no. 

 

Neutral elevator trim is needle horizontal. 

 

In the the experience of my squad those with spring tension joysticks should trim one division nose up; those with FFB sticks one division nose down. 

[grafspee]

14 minutes ago, DD_Fenrir said:

 

Er.... no. 

 

Neutral elevator trim is needle horizontal. 

 

In the the experience of my squad those with spring tension joysticks should trim one division nose up; those with FFB sticks one division nose down. 

I use neutral trim, It is just perfect. With 1 notch up plane like to pitch up early at take off. With neutral trim it fly off with out any pitch intput.

 

Edited January 12, 2021 by grafspee

[Holbeach]

2 hours ago, DD_Fenrir said:

 

Er.... no. 

 

Neutral elevator trim is needle horizontal. 

 

In the the experience of my squad those with spring tension joysticks should trim one division nose up; those with FFB sticks one division nose down. 

2 notch down from initial position is 0 deg. (neutral).

..

[DD_Fenrir]

Yes. I think the confusion come from on spawning in game where the initial position is 2 divisions nose up.

 

The reason being is that the trim tabs have unequal angular travel. 7° below the elevator chord-line (for max nose up trim), 20° above (for max nose down). The gauge however is equidistant between fully nose up and fully nose down, with the needle at the three o'clock/horizontal position exactly between representing neutral trim.

 

Ergo when the trim tab chord-line is aligned with elevator chord-line (i.e. the trim tab appears flush with the elevator) the trim tab indicator will still show about 1/3rd up.

 

This how ED have modeled the datum for neutral elevator trim position; with the tab aligned with the elevator. This is how we spawn in.

 

However this is NOT neutral trim.

 

Most aircraft are designed as closely as practicable to find their trim neutral point - without trim input - at cruise speed and power settings with a less than full fuel load. I would be surprised if the Spitfire was not the same. 

 

Even when cruising straight and level, the elevator itself is significantly displaced down from the horizontal stabiliser. When I asked Yo-yo himself as to why, as an aerodynamicist, he thought this was the case, he said to to account for the wings downwash.

 

So it appears to the observer that the Spitfire, during cruise has elevator nose down input; however this is the neutral position of the elevator (or as near to it as airspeed and power settings allow) and to maintain this position the trim tab must be displaced above the elevator chord-line to maintain it's relation to the horizontal stabiliser's chord-line.

 

Ultimately it boils down to the fact that most pilots approaching the Spit were - and still are - unaware of this peculiarity of geometry. They went by the Pilot's Notes and the gauges.

 

Ergo the first and correct assumption is that Trim Neutral is the midpoint between both extremities of the trim gauge. Anything else would be hugely disingenuous if not downright dangerous to a new pilot and as such if any such peculiarity of interpretation of that gauge was required it would have had to have been explained within the Pilot's Notes.

 

 

Edited January 12, 2021 by DD_Fenrir

[Nealius]

Well this is weird. I see people saying they can takeoff with no pitch input at neutral trim, but for me my nose will pitch up and the left wing will dip. I'm always at 1 division down or 1.5 divisions down and still get a minor, but controllable, ptich and dip.

[reece146]

I find the intensity of the pitch/dip varies with the speed at which you slide the throttle forward. Torque effects I guess.

 

FWIW, I typically slide the throttle forward slowly initially until I can feel the rudder "bite" and be useful against the air flow - then I start moving the throttle forward faster but not slammed forward. Runways are long - no reason for it. I spent hours and hours doing touch-n-goes to get the feel of it. It is very distinct/noticeable once you feel it. There's also the urge to over-correct regardless of curves - if you think 30% rudder is needed, try 15-20% and see if you can balance the "momentum" of the plane fishtailing left and right (with tail wheel off the ground I mean).

 

Full disclosure: still struggle some days - not an expert DCS Spit pilot by any means - just sharing my experience in hopes it helps someone.

[grafspee]

I assumed that horizontal trim setting is neutral trim, then what ever this trim is called i use this. Then i don't need to push stick to avoid stalling while taking off.

Even taking off with max boost.

Edited January 15, 2021 by grafspee

[Holbeach]

I've always used the neutral trim, (0) and full right rudder trim, for a smooth take off.

With drop tanks or a bomb, the default still works, (+2), but plus 1 is better.

 

This also works in another sim.

 

..

[reece146]

yeah, 0 to -1 range depending on how much of a rush I'm in to get off the ground (don't go into analysis paralysis to make it exact).

[flyco]

I set 1 degree nose-down, for take off, start with full aft stick, and use around 8" of boost (rudder full right trim).  Once the IAS exceeds around 80, i gently let the stick go forward to neutral and it flies itself of.  Once I am above 120 kias, I ease back very slightly, confirm a positive ROC and then retract the undercarriage (not the gear - this is a 1940's RAF aircraft!).

 

Its the bit from 0 to 80 kias and from 120 kias to 0 that I have problems with!!